A number of isoindole-type compounds are known in the prior art. Recently, in German Offenlegungsschrift 2,165,651 a group of isoindole-1,3-diones which are useful as herbicides was disclosed. The general formula for the isoindole-1,3-diones disclosed in the Offenlegungsschrift is as follows: ##SPC2##
Wherein R may be an aryl, aralkyl or benzyl optionally substituted with 1 to 5 halogen atoms; hydroxy, nitro, cyano, thiocyano, carboxy, halogenated alkyl, or alkyl, or alkoxy, lower alkylthio, phenyl groupings and a group having the configuration -O-CH.sub.2 A may also be substituted therein, wherein A is a phenyl or a naphthyl group, wherein the phenyl group may have one or more substitutions therein, such as halogen atoms, nitro groupings, lower alkyl groupings or lower alkoxy groupings.
Typical of the compounds disclosed in the Offenlegungsschrift is the compound of Example 1: ##SPC3##
In U.S. Pat. No. 2,900,243 there is a disclosure of herbicidal activity for 2-(4-halophenyl)-3a,4,5,6,7,7a-hexahydro-1H-isoindole-1,3(2H)-diones; the phenyl and 2-chlorophenyl analogs are described as being inactive as herbicides at application rates of 25 lbs/acre.
None of the compounds which are disclosed above have demonstrated high herbicidal activity in conjunction with virtually no damage to the crop which is to be protected. That is to say, if any of the compounds was an effective herbicide it tended also to damage crops. The compounds of this invention are effective herbicides which may be used for selective weed control in certain crops, particularly rice.
According to the instant invention, compounds have been discovered which have high herbicidal activity with seletivity for certain crops.